Table of Contents
Reviewed and updated by ICD - Week 44/2026
Blown film is cooled by air, in a slower process, with better cling but less uniform thickness and a higher cost; cast film is cooled quickly on chill rolls, is more uniform, comes off the line in high volume so it costs less, and clings less. That is what Wikipedia records about the two ways of making stretch film. For the rest, tear resistance, puncture resistance and noise when unwinding, commercial sources do not agree, so this article separates what has a technical source from what you need to test on your own pallets.
- The root difference is how the film is cooled: by air (blown) or on chill rolls (cast)
- Cast film is more uniform in thickness and clearer; blown film clings more and has better-balanced mechanical properties
- Tear and puncture strength depend on the resin, the number of layers and the thickness, not just the production method
- Choose by testing at the same thickness and the same pre-stretch, then measure the film used per pallet
This article is for buyers of pallet wrap and warehouse engineers who need to choose between blown and cast film. Every claim is sourced; where no neutral source exists, we say plainly that no conclusion can be drawn yet.
How are blown film and cast film made differently?
Both start from molten resin, usually LLDPE; the difference is the shape of the die and how the film is cooled. Blown film extrudes resin through a ring die into a tube, inflates it with air like a bubble and cools it with air. Cast film extrudes through a flat slot die and runs over cooling rolls, so it cools very quickly. This cooling speed accounts for most of the differences that follow.
According to Wikipedia, the resin type matters just as much: LLDPE made with hexene or octene comonomer gives better elongation at break and puncture resistance than the butene type. That means two rolls that are both cast film but have different base resins can still perform very differently.
How do the two differ, according to technical sources?
The criteria below all have neutral technical sources. The uniformity figures come from plastics industry association material on polyolefin film in general, not stretch film alone, so read them as a trend and not as the specification of one particular roll.
| Criterion | Blown film | Cast film | Source |
|---|---|---|---|
| Cooling method | By air, slow | On chill rolls, fast | Wikipedia; SPE Extrusion Division |
| Thickness uniformity | Typically within about ±10%, can reach ±5% with automatic control | Typically within about ±2% | SPE Extrusion Division |
| Clarity, gloss | Slow cooling gives more crystallization, higher haze | Fast cooling gives less haze, glossier | SPE Extrusion Division; TAPPI |
| Balance of mechanical properties in both directions | More balanced between machine and transverse directions, depending on blow-up ratio | Oriented mainly in the machine direction | SPE Extrusion Division; TAPPI |
| Cling of stretch film | Higher | Lower | Wikipedia |
| Output and cost | Lower output per hour, higher cost | High output, lower cost | Wikipedia; TAPPI |
Two notes for reading the table correctly. First, SPE points out that cast film is more uniform because the die gap can be adjusted point by point by computer, while blown film can also narrow its deviation when an automatic thickness control system is fitted. Second, cling is not caused by the production method alone: it also depends on the cling additive and the layer structure of each roll, so two rolls of the same type can still cling differently.
Tear, puncture and noise: why do we draw no conclusion?
Most supplier literature describes blown film as more puncture resistant and cast film as quieter to unwind, but these documents contradict each other on many other points, which is why we do not treat them as conclusions. One source says blown film clings on only one side, another says cast film is the one that clings on both sides; one ranks cast film better for tear resistance, another ranks blown film higher. They are written for buyers by sellers of their own type of film, and rarely say what thickness, resin or number of layers they compared.
Neutral sources do not allow a general conclusion either. SPE points out that blown film’s mechanical properties are more balanced between the two directions, but that is a remark about polyolefin film in general, and a study by Billham and colleagues on polyolefin film shows that tensile strength, elongation at break and tear propagation strength all differ between blown and cast film, depending on resin type and blow-up ratio. So the right question is which film can withstand your pallet, not which is better.
Choosing blown or cast film by need
A sound approach is to start from your needs and then match them against the sourced points in the table above, rather than starting from the name of the film. The table below gives a leaning only where the technical source is strong enough; where no source exists it says testing is needed.
| Need | Leaning | Basis |
|---|---|---|
| Automatic wrapping machine, consistent thickness between pallets | Lean toward cast film | Better thickness uniformity (SPE), more uniform film (Wikipedia) |
| Need to see labels or scan barcodes through the film | Lean toward cast film | Less haze, glossier (SPE) |
| Need low cost per roll | Lean toward cast film, then measure film use per pallet | High output, lower cost (Wikipedia) |
| Need high cling so the load hugs tightly | Lean toward blown film, but test because additives matter | Higher cling (Wikipedia) |
| Sharp-edged goods prone to puncture | No conclusion yet, test both on real pallets, add corner protectors | Commercial sources disagree, neutral sources are not enough |
A reliable test keeps everything the same except the film type: the same thickness, the same number of layers, the same pre-stretch, the same number of wraps and the same overlap. Then weigh the film used per pallet. ASTM D4649 is the guide to selecting and using stretch film that buyer and seller can use together to agree specifications before comparing prices.
Four common mistakes when comparing two films
The first mistake is comparing price per kilogram without measuring the film used per pallet; a heavier film wrapped in fewer turns can be cheaper per pallet. The second is choosing thinner film and then adding wraps, which saves nothing overall. The third is not testing with sharp edges, pallet corners and the real pulling force of the wrapping machine. The fourth is ignoring the need to scan barcodes or read labels after wrapping, since clarity is one sourced difference between the two types.
With a wrapping machine, the film also has to suit the equipment: if you are considering a film change for a wrapping machine already in service, test it over a short shift and monitor film breaks, film use and how well the load is held. ICD Vietnam’s PE film range lists the specifications to check when you need to talk with the technical team.
Frequently asked questions
What is the root difference between blown PE film and cast PE film?
How the film is cooled. Blown film is extruded through a ring die, inflated and cooled by air; cast film is extruded through a slot die and cooled quickly on chill rolls. Most of the difference in uniformity, clarity and cost comes from this.
Which film is more uniform in thickness?
Cast film. SPE Extrusion Division gives typical thickness deviation of about ±2% for cast film and about ±10% for blown film, which can reach ±5% with automatic control; these figures are for polyolefin film in general.
Which film clings better?
According to Wikipedia, blown film clings better. However, cling also depends on additives and layer structure, so test the specific roll.
Which film is cheaper?
According to Wikipedia, cast film costs less because of high output per hour. But the real cost per pallet also depends on the amount of film used, so measure it instead of comparing price per kilogram alone.
Is blown film more puncture resistant than cast film?
Commercial sources usually say yes, but they disagree and do not state thickness, resin or number of layers. Neutral technical sources show that mechanical properties depend on resin type and blow-up ratio. For sharp-edged goods, test both on a real pallet.
Which type should an automatic wrapping machine use?
There is no general answer. Cast film has an advantage in thickness uniformity, which automatic machines need; but test it on your own machine and monitor film breaks, film use and how well the load is held.
Contact ICD Vietnam
- ICD Vietnam PE film and wrapping machines: specification advice and film selection by load
- Northern Vietnam hotline: 0983 797 186 | 090 345 9186
- Southern Vietnam hotline: 098 6784 186
- Email: sales@icdvietnam.com.vn
- Zalo: Chat Zalo
References
- Stretch wrap, Wikipedia (how blown and cast film are made, cling, cost, the role of the LLDPE type).
- Blown film versus the cast film process, SPE Extrusion Division (thickness uniformity, optical properties, balance of mechanical properties).
- Why Choose Blown, Cast or Lamination Processes to achieve Barrier Properties?, TAPPI (comparison of blown and cast processes and uniformity).
- The Effect of Extrusion Processing Conditions on the Properties of Blown and Cast Polyolefin Packaging Films, Billham et al. (mechanical properties depend on the blown or cast process and the resin type).
- ASTM D4649-20 Standard Guide for Use of Stretch Films and Wrapping Application, ASTM International.
